Conducting polymers have recently attracted much attention because they are flexible, easy to process and very useful in reducing the size of a variety of electronic instruments.
Many kinds of the conducting polymer are heretofore known; typically, polyacetylene, polythiophene, polypyrrole, poly-p-phenylene or their derivatives, each of which has a one-dimensional .pi. conjugation spreading like a chain. On the other hand, polyacene has a two-dimensional .pi. conjugation spreading like a ladder. Conductivity values of these polymers after being doped are on the order of 10.sup.-5 to 10.sup.-3 S/cm.
Application of the polymers, however, was greatly restricted for the following reasons.
Polyacetylene, which is generally unstable in an oxygen-containing environment, is readily oxidized. Although aromatic polymers such as polythiophene, polypyrrole or poly-p-phenylene are stable in air, they and their doped conducting polymers are not as conductive as metal. This is because their energy band gap (Eg) before being doped is large compared to that of polyacetylene. The ladder-like polymers such as polyacene also have disadvantages; they are less soluble, and, in turn, hard to process into a desired shape and thus difficult to control when constructing products.
Polymers like polyacetylene, polythiophene, polypyrrole, poly-p-phenylene and their derivatives and polyacene, and polymer-based compositions thus have had great restrictions for practical use, since they are poor in conductivity, solubility and stability in air.
The invention provides a highly conductive and stable polymer and a polymer-based composition containing the polymer as a principal component.